Over a dozen Fortune 500 companies have signed a pledge, organized by the White House, to take measures to curb greenhouse gas emissions and invest in clean energy. The White House announced the news on Monday, and the Obama administration is hosting the companies later today.

The companies include tech firms Apple, Google and Microsoft, beverage giants Coca-Cola and PepsiCo, industrial companies Alcoa and Cargill, and banks Goldman Sachs and Bank of America. Also included were Warren Buffett's Berkshire Hathaway Energy, which has made major investments in wind and solar farms, huge package delivery company UPS, auto giant General Motors, and the largest company in the world Walmart.

The sheer size of these companies is a big deal. The companies generated a combined $1.3 trillion in revenue in 2014 and have a total combined market cap of $2.5 trillion. The companies' pledges would deliver $140 billion in investment that could lower carbon emissions, and create 1.6 gigawatts of new clean energy projects. One gigawatt is about the same amount of energy as a large natural gas plant delivers.

Many of these companies have made commitments to clean energy and energy efficiency for financial reasons. Companies like UPS and Walmart can lower their fuel costs by cutting fuel use. Berkshire Hathaway Energy is investing in solar energy because solar is a rapidly growing industry. Apple is buying solar power because it can save the company money on energy costs over time.

But the news shows how the Obama Administration, and these Fortune 500 firms, are eager to change the political conversation in the U.S. around clean energy and climate change in the run up to the United Nation's climate change-focused conference in Paris at the end of the year. At that event, countries around the world set targets for lowering their nations' greenhouse gas emissions.

In years past, the issues of clean energy and climate change have been highly politicized in the U.S. High profile failures like Solyndra — a solar startup that took government funds and went bankrupt — have dominated the clean energy conversation in previous election years.

The Paris convention, called COP21, will be the 21st annual meeting from the United Nations on this topic. In previous years, international businesses have played a substantial role influencing the negotiations.

By signing the White House pledge, the companies agree to support a "strong" outcome from the Paris talks, agree to new investments in clean energy and reducing carbon emissions, and agree to provide leadership around fighting climate change.